Ferguson and Benitez, who was manager of Liverpool for six years, clashed on multiple occasions but most notably when the Spaniard unleashed an incredible rant in January of the 2008-09 Premier League where he accused the United boss of getting away with things other managers could not.

Writing in his autobiography, released on Tuesday, Ferguson said: "The mistake he made was to turn our rivalry personal. Once you made it personal, you had no chance because I could wait. I had success on my side. Benitez was striving for trophies while also taking me on. That was unwise.

"So, on television puts his glasses on and produces this sheet of paper. Facts. The facts were all wrong. All I said in reply was that Rafa was obviously bitter about something. That was me saying to him: look, you're a silly man. You should never make it personal.

"The advance publicity was that Benitez was a control freak, which turned out to be correct."

Ferguson also added that, when it came to choosing a winner between his old rivals, Jose Mourinho was the better manager, writing: "Jose Mourinho was far more astute in his handling of players. And he has personality. If you saw Jose and Rafa standing together on the touchline, you knew you could pick the winner."

In quotes that will further anger Liverpool fans, Ferguson also wrote about Kenny Dalglish's return as Reds manager and poked fun at the amount of money paid for Stewart Downing and other new signings.

"Stewart Downing cost 20 million pounds,” he wrote. “He had talent but was not the bravest or quickest. 20 million pounds?

"For Liverpool to return to the level of us and Manchester City was clearly going to require huge investment. Anfield has not moved on. Even the dressing rooms are the same as 20 years ago.

"My reading of their squad was that they needed eight players to come up to title-winning standard."